1. Field
The present disclosure relates generally to electrosurgery and electrosurgical systems and apparatuses, and more particularly, to an electrical leakage detection method and system for use with laparoscopic electrosurgical instruments.
2. Description of the Related Art
The term “laparoscope” comes from two Greek words. The first is lapara, which means “the soft parts of the body between the rib margins and hips”, or more simply, the “flank or loinn”. The other Greek root is skopein, which means “to see or view or examine”. Skopein has become scope in English. Therefore, a laparoscope is an instrument through which structure within the abdomen and pelvis can be seen. A small surgical incision is made in the abdominal wall to permit the laparoscope to enter the abdomen or pelvis. A diversity of tubes can be pushed through the same incision or other small incisions permitting the introduction of probes and other instruments. In this way, a number of surgical procedures can be performed without the need for a large surgical incision. Among the instruments used during a laparoscopic procedure are electrosurgical instruments.
Laparoscopic surgery, a “minimally invasive” procedure, is commonly (but not exclusively) used to treat diseases of the gastrointestinal tract. Unlike traditional surgery on the colon or other parts of the intestines where a long incision down the center of the abdomen is required, laparoscopic surgery requires only a small “keyhole” incision in the abdomen. As a result, the person undergoing the procedure may experience less pain and scarring after surgery, and a more rapid recovery.
Electrosurgery is a term used to describe the passage of high-frequency (i.e., radio frequency) electrical current through tissue to create a desired clinical tissue effect. Through this technique, the target tissue, acting as a resistor in an electrical circuit, is heated by its conduction of the electrical current. Electrocautery, as distinguished from electrosurgery, uses an electrical current to heat a surgical instrument, which in turn conveys that heat to the target tissue. Electrosurgical electrode tips remain cool while targeted tissues heat up, primarily because the electrodes have much lower impedance than the adjacent targeted tissues. Electrosurgical tissue effects include cutting, coagulation, desiccation and fulguration. In addition, modern electrosurgical generators can create blended modes of operation under which a surgeon can for example, cut and coagulate simultaneously.
In electrosurgery, there are two types of electrodes: mono-polar and bipolar. Mono-polar electrodes pass RF electrical current from an electrosurgical generator through an active electrode into targeted tissue, through the patient, the dispersive electrode (e.g., a return electrode or pad), and back into the electrosurgical generator. If the return electrode is properly placed relative to the patient and surgical site, the electrosurgical tissue effects occur only at the active electrode and not the dispersive electrode. On the other hand, bipolar electrodes are arranged in pairs (or poles, “+/−” and “−/+”) and form part of the surgical instrument (e.g., electrosurgical forceps) without the need for a separate return electrode (grounding) plate attached to the patient. The intended flow of current is between the pair of bipolar electrodes (from “+/−” to “−/+”), which are usually close together and use relatively low voltage.
There are a number of well-known complications that may arise during laparoscopic electrosurgery. There are two major types of such complications pertinent to this discussion. The first derive from injuries caused by operator (i.e., surgeon) error such as direct coupling, perforation and laceration of targeted and non-targeted tissues. These injuries are outside the scope of this discussion. The second group of complications occurs when targeted tissues get burned from stray electricity emitting from or caused by other than operator error. There are two primary types of stray electricity applicable here.
The first type, insulation failure, involves faults in the insulation of the electrosurgical instrument—even a microscopic defect—that permit leakage of electrical current. The coating over metallic electrosurgical instruments intended to insulate then can be weakened by (i) repeated insertions into and removals from the patient, (ii) use of high voltage, (iii) material defects, and (iv) multiple sterilizations. A small hole in the insulation can represent a higher risk of injury from stray current than a larger hole because of its concentrating effect on the current density for such a leakage.
The second type of stray electricity results from capacitive coupling. Capacitive coupling occurs through instantaneous current induction between instruments, or between an instrument and adjacent tissues. This phenomenon can occur even though the insulation is completely intact. Capacitive coupling requires a capacitor, which is created when two conductors are separated by an insulator. The risk of this type of stray electricity can increase when surgeons use disposable and reusable instruments together during the same laparoscopic electrosurgical procedure.
The clinical complications from stray current caused by insulation failure and capacity coupling are particularly challenging because their initial presentation often mimics normal post-surgical symptoms of laparoscopy: namely, non-specific abdominal pain and slight to moderate fever. These clinical complications include perforation, blood vessel damage, organ damage, and peritonitis. All of these, particularly fecal peritonitis, can lead to severe or fatal infection. Since injuries resulting from stray current are most often undiscovered until days after surgery, and are often masked by unrelated conditions, prevention of these injuries cannot be overstressed.